More than four years after going public, Twitter has finally posted its first profitable quarter. Today’s Q4 earnings results boasted a net profit of $91 million and $732 million in revenue—well above analyst expectations and driven by Twitter’s continued investment in video. Twitter’s stock jumped by more than 20% in early trading, the highest it has been since mid-2015.

That said, Twitter’s user numbers remain unchanged since last quarter, which the company admits is partially the result of cracking down on fake accounts, spam, and malicious activity. (Twitter reported 330 million monthly users, a 4% increase from the same quarter last year.) It’s possible Twitter’s user base in the U.S.—which has hovered around 68 million for over a year—just won’t budge much at this point. The company insists on heralding its daily user growth, which is up 12% year-over-year, but we still have no clear idea how large that number really is.

One thing that may give shareholders pause: Twitter COO Anthony Noto is leaving next month to take the reins of online lender SoFi. Noto helped steer Twitter through its IPO while at Goldman, and then joined the company in 2014. He’s been a key figure since—so it’s unclear what Twitter might look like without him.